In the drilling and completion industry, it is often desirable to isolate one portion of a well bore from another. In some cases, each portion of the well bore may be treated in order to stimulate production. Various tools may be used to operate sleeves disposed along a tubing string extending into the wellbore. For example, a drop ball may be introduced into a drill string to shift a sleeve and expose stimulation ports. Another drop ball may be introduced to shift another sleeve closing the stimulation ports and opening production ports.
Prior to initiating production, it is desirable to remove the drop balls from the tubing string. There are a number of techniques for removing drop balls. A tool may be run into the wellbore from a surface system to drill out the drop balls; the drop balls may be forced through corresponding ball seats by pressure introduced from the surface system. The use of tools is a time consuming and expensive undertaking. The use of pressure is also time consuming Drop balls may also be allowed to degrade. Specifically, drop balls may be made from a material designed to degrade when exposed to selected environmental factors.
It may be desirable to accelerate degradation of the drop balls. In such a case, an accelerant may be introduced into the tubular string to speed up degradation of the drop balls. The accelerant, typically a fluid having selected properties, is introduced into the tubular string and pumped down to the top most drop ball. Given the presence of fluid already in the tubular string, a large amount of accelerant is required to be introduced. The large amount of accelerant increases a likelihood that some of the accelerant will contact and react with the drop ball. This process is repeated for each drop ball until the tubular string is free of obstruction. Introducing an accelerant in this manner is a time consuming and expensive undertaking. Therefore, the industry would be receptive to more effective methods for removing drop balls.